Piezoelectric power generator and wireless sensor network apparatus

Abstract

A piezoelectric power generator that includes a piezoelectric multilayer body including a piezoelectric element that converts vibration into electricity and a substrate on which the piezoelectric multilayer body is mounted. The resonant frequency of the piezoelectric element coincides with the reference of the substrate so that the piezoelectric element efficiently vibrates. The addition of vibration portions in the substrate allows various resonant frequencies to be set.

The invention claimed is: 
     
       1. A piezoelectric power generator comprising:
 a substrate having at least one vibration portion; and 
 a piezoelectric element that converts vibration into electricity mounted on the substrate, the piezoelectric element having at least one vibration portion, 
 wherein a mass of the at least one vibration portion of the substrate is larger than a mass of the at least one vibration portion of the piezoelectric element, and 
 wherein the piezoelectric element is configured to vibrate in a bending vibration mode, and a resonant frequency of the substrate coincides with a resonant frequency of the bending vibration mode. 
 
     
     
       2. A piezoelectric power generator comprising:
 a substrate having at least one vibration portion; and 
 a piezoelectric element that converts vibration into electricity mounted on the substrate, the piezoelectric element having at least one vibration portion, 
 wherein a mass of the at least one vibration portion of the substrate is larger than a mass of the at least one vibration portion of the piezoelectric element, and 
 wherein a resonant frequency of the at least one vibration portion of the substrate coincides with a resonant frequency of the piezoelectric element. 
 
     
     
       3. The piezoelectric power generator according to  claim 2 , wherein the at least one vibration portion of the substrate is defined by a notch. 
     
     
       4. The piezoelectric power generator according to  claim 1 , wherein the at least one vibration portion of the substrate includes a first vibration portion and a second vibration portion, and a resonant frequency of the first vibration portion and a resonant frequency of the second vibration portion are different from each other. 
     
     
       5. A wireless sensor network apparatus comprising:
 a substrate having at least one vibration portion; 
 a piezoelectric power generator mounted on the substrate, the piezoelectric power generator including a piezoelectric element having at least one vibration portion and configured to convert vibration into electricity; 
 a wireless communication apparatus mounted on the substrate; and 
 a sensor element mounted on the substrate, 
 wherein a mass of the at least one vibration portion of the substrate is larger than a mass of the at least one vibration portion of the piezoelectric element, and 
 wherein the piezoelectric element is configured to vibrate in a bending vibration mode, and a resonant frequency of the substrate coincides with a resonant frequency of the bending vibration mode. 
 
     
     
       6. The wireless sensor network apparatus according to  claim 5 , wherein the wireless communication apparatus includes an antenna. 
     
     
       7. A wireless sensor network apparatus comprising:
 a substrate having at least one vibration portion; 
 a piezoelectric power generator mounted on the substrate, the piezoelectric power generator including a piezoelectric element having at least one vibration portion and configured to convert vibration into electricity; 
 a wireless communication apparatus mounted on the substrate; and 
 a sensor element mounted on the substrate, 
 wherein a mass of the at least one vibration portion of the substrate is larger than a mass of the at least one vibration portion of the piezoelectric element, and 
 wherein a resonant frequency of the at least one vibration portion of the substrate coincides with a resonant frequency of the piezoelectric element. 
 
     
     
       8. The wireless sensor network apparatus according to  claim 7 , wherein the at least one vibration portion of the substrate is defined by a notch. 
     
     
       9. The wireless sensor network apparatus according to  claim 6 , wherein the at least one vibration portion of the substrate includes a first vibration portion and a second vibration portion, and a resonant frequency of the first vibration portion and a resonant frequency of the second vibration portion are different from each other. 
     
     
       10. The wireless sensor network apparatus according to  claim 7 , wherein the wireless communication apparatus includes an antenna. 
     
     
       11. The wireless sensor network apparatus according to  claim 7 , wherein the at least one vibration portion of the substrate includes a first vibration portion and a second vibration portion, and a resonant frequency of the first vibration portion and a resonant frequency of the second vibration portion are different from each other. 
     
     
       12. The piezoelectric power generator according to  claim 2 , wherein the at least one vibration portion of the substrate includes a first vibration portion and a second vibration portion, and a resonant frequency of the first vibration portion and a resonant frequency of the second vibration portion are different from each other.